Expansion anchor for use in support structures of relatively soft material

ABSTRACT

An expansion anchor sleeve is composed of two elongated shell sections of U-shaped cross-section whose open sides face one another and are bounded by juxtaposed edge faces. A transverse recess is provided in the front portion of the sleeve tapering towards the rear portion and bounded by sections of the aforementioned edge faces on which an expander member, located in the recess, rides when it is drawn rearwardly by a threaded actuating member.

United States Patent [191 Fischer EXPANSION ANCHOR FOR USE IN SUPPORTSTRUCTURES OF RELATIVELY SOFT MATERIAL V Inventor: Artur Fischer,Altheimer Strasse 219, Tumlingen, Germany [22] Filed: Aug. 30, 1971 [21]Appl. No.: 176,121

[30] Foreign Application Priority Data Sept. 3, 1970 Germany P 20 43621.9

[52] US. Cl. 85/76 [51] Int. Cl. Fl6b 13/06 [58] Field of Search 85/76,75, 88, 86, 85/87, 77, 73, 74

[56] References Cited UNITED STATES PATENTS 1,109,955 9/1914 Barrett85/76 3,623,396 11/1971 Mortensen 85/75 13,177 7/1855 London et a1.85/76 [451 Oct. 16, 1973 3,366,000 1/1968 Bennett 85/72 1,019,723 3/1912Pauli 85/77 1,471,911 10/1923 Ogden et al. 85/76 FOREIGN PATENTS ORAPPLICATIONS 767,444 10/1934 France 85/76 430,603 8/1911 France 85/76Primary Examiner-Edward C. Allen Attorney-Michael S. Striker [5 7]ABSTRACT An expansion anchor sleeve is composed of two elongated shellsections of U-shaped cross-section whose open sides face one anotherand'are bounded by juxtaposed edge faces. A transverse recess isprovided-in the front portion of the sleeve tapering towards the rearportion and bounded by sections of the aforementioned edge faces onwhich an expander member, located in the recess, rides when it is drawnrearwardly by a threaded actuating member.

'scmns, niawia m EXPANSION ANCHOR FOR USE IN SUPPORT STRUCTURES OFRELATIVELY SOFT MATERIAL BACKGROUND OF THE INVENTION The presentinvention relates generally to anexpansion anchor, and more particularlyto an expansion anchor which is especially intended for use in supportstructures of relatively soft material, such as porous matter includingporous concrete.

Expansion anchors are already well known in a substantial variety ofdifferent types. Many of these operate by drawing a usually conicalexpander member into a slotted expansion anchor sleeve from the leadingend towards the trailing end of the same, thereby radially spreading thesleeve into frictional engagement with the wall surrounding a bore inthe support structure in which the expansion anchor is to be retained.

This type of expansion anchor is entirely sufficient for affording thenecessary frictional retention of the expansion anchor againstwithdrawing forces from the expansion anchor hole, provided that theexpansion anchor is used in a support structure-such as masonrywhich iscomposed of rather hard material. It is possible with this type ofexpansion anchor to expand the sections into which the expansion anchorsleeve is subdivided by longitudinally slotting it, to an extent whichis greater than the outer diameter of the expander member by twice thewall thickness of the sleeve. The situation is different, however, ifthe material of the support structure in which the expansion anchor isto be retained is relatively soft -for instance porousand will tend tocrumble or collapse when the sleeve is expanded and attempts to contactit under pressure. This means that the material surrounding theexpansion anchor hole will crumble and its integrity be destroyed, sothat a conventional expansion anchor sleeve of the type mentioned abovecan be withdrawn without any significant resistance, when it has beenanchored in an expansion anchor hole provided in a support structure ofsuch relatively soft material.

Of course, the realization that this porblem exists is not new. Attemptshave already been made to overcome it, for instance by providing theouter surface of the expansion anchor sleeve with projections or teeth.The purpose is that for the teeth to bite into the surrounding materialof the support structure when the sleeve is expanded and to therebyincrease the resistance of the sleeve to undesired withdrawal from theexpansion anchor hole. Promising as this approach may appear at firstsight, it has been found that even the provision of such teeth orprojections does not significantly increase the resistance of the sleeveto withdrawal from an expansion anchor hole formed in a supportstructure of relatively soft material. The reason is that the strengthof the bond between the support structure material particles locatedbetween the teeth and those located exteriorly of the teeth is notsufficient, so that forces acting upon the expansion anchor sleeve in asense tending to withdraw it from the expansion anchor hole result inshearing'off of the particles which are located between the teeth fromthe particles which are located exteriorly of the teeth.

There is, in fact, to my knowledge no expansion anchor in existence inthe prior art which satisfactorily meets the aforementioned requirementsand overcomes the aforementioned disadvantages.

SUMMARY OF THE INVENTION It is, accordingly, an object of the presentinvention to provide such an expansion anchor which meets theaforementioned requirements and overcomes the disadvantages of the priorart.

It is in particular an object of the present invention to provide suchan expansion anchor which is especially suitable for use in supportstructures of relatively soft material, and which when used inconjunction with such support structures will provide an expansionability substantially greater than what is known from the prior art witha concomitant increase in the resistance of it to undesired withdrawalfrom the expansion anchor hole.

An additional object of the invention is to provide such an expansionanchor which is simple and relatively inexpensive to construct.

With the above objects in view, and others which will become apparenthereafter, one feature of the invention resides in an expansion anchorfor use in support structures of relatively soft material, which anchorcomprises, briefly stated, an expansion anchor sleeve having a frontportion and a rear portion and including a pair of elongated shellsections of substantially U- shaped cross-section having facing opensides bounded by juxtaposed edge faces. A transverse recess is providedin the front portion of the sleeve, being bounded by sections of theedge faces which converge in direction from a leading end 'of the frontportion towards the rear portion of the sleeve. An expander member islocated in this recess extending transverse of the elongation of thesleeve, and threaded means extends from the region of the rear portiontowards the leading end and is fast with the expander member. With thisexpansion anchor according to the present invention, turning of thethreaded means in requisite sense will result in displacement of theexpander member in direction towards the rear end in sliding engagementwith the edge faces, leading to concomitant outward deflection of theshell sections at least in the region of the front portion.

Of course, it will be appreciated that the dimension of the expandermember in direction transverse to the longitudinal axis of the expansionanchor sleeve must correspond at least to the outer diameter of thesleeve in the region of the plane of separation of the twosh'ellsections. This is necessary to assure that the expander member willslide on the juxtaposed edge faces of the shell sections when it iswithdrawn in a sense tending to expand the sleeve. It has been foundparticularly advantageous to construct the expander member incylindrical or substantially cylindrical configuration, in order tothereby reduce the friction between the expan der member and the edgefaces on which it slides during expansion, whereby the force requiredfor effecting such expansion is held to a minimum. The longitudinal axisof the cylindrically configurated expander member of course extendstransversely to the longitudinal axis of the sleeve and the expandermember may be of one piece with a threaded actuating screw or bolt bymeans of which it is drawn towards the rear end of the sleeve or it maybe connected with this screw or bolt in suitable manner, for instancevia a screw connection. When an expansion anchor sleeve of the novelexpansion anchor is expanded in this manner, the shell sections aredisplaced radially outwardly away from one another, and the minimumradial expansion will be determined by the diameter of the expandermember and double the depth of the U-shaped cross-section of therespective shell sections. In actual fact, however, the expansionobtained is significantly greater because the U-shaped cross-sectionalconfiguration of the shell sections makes the latter so rigid that theirbending or deflection inwardly towards one another at opposite sides ofthe expander member (as seen with respect to the longitudinal axis ofthe sleeve) is practically impossible. The expanding shell sections tendto force the soft and- /or porous material of the support structurewhich surrounds the expansion anchor hole ahead of themselves and tocompact it. It will be appreciated that the greater the angle ofexpansion of the shell sections is, the greater will be the amount ofsupport structure material which is engaged and compacted. The amount ofsuch material is determinative of the resistance which the expansionanchor sleeve can oppose to a force tending to withdraw it from theexpansion anchor hole, so that the present expansion anchor isparticularly advantageous and highly effective for use in supportstructures of porous and/or soft material.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective viewillustrating one embodiment of the novel expansion anchor;

FIG. 2 is a view similar to FIG. 1 but illustrating another embodimentof the expansion anchor;

FIG. 3 is an axial section showing the expansion anchor of FIG. 1anchored in a support structure; and

FIG. 4 is a fragmentary somewhat diagrammatic detail view of the frontend portion of an anchor similar to FIG. 1 but illustrating anadditional embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing indetail, and firstly the embodiment illustrated in FIGS. 1 and 3, it willbe seen that the novel expansion anchor has an expansion anchor sleeve 1which is composed of two elongated shell sections 4a and 4b which are ofsubstantially U-shaped cross-section with their open sides facing oneanother. The open sides of each shell section are bounded bylongitudinally extending edge faces each of which has a section 11inclined with respect to the longitudinal axis of the sleeve 1, and asection 12 which extends in substantial parallelism with thislongitudinal axis.

In the region of the trailing portion of the sleeve, the shell sections4a and 4b are connected with one another. Such connection can beeffected in various ways, for instance by spot welding, bytongue-and-groove connections, or in other ways, so that the sleeve 1can be assembled from two identical shell sections which are connectedwith one another. In the embodiment of FIGS. 1 and 3 the connection isillustrated at 3 and is here in form of interlocking or interengagingnotches and projections on the respective shell sections 4a and 4b, thisbeing a particularly advantageous way of connecting the shell sectionswith one another. These notches and projections can also be soconstructed that they serve as a guide for the threaded means, hereillustrated as a screw or bolt 5 which cooperates with a nut 6. Guidanceso provided prevents lateral yielding of the screw or bolt 5 during useof the expansion anchor.

In the region of the leading end 10 at the front portion of the sleeve1, the sections 11 of the edge faces define with one another a recess 9which converges or tapers in direction towards the trailing end portionor rear end portion 2 of the sleeve, and located in this recess 9 is anexpander member 7 which is here of cylindrical configuration and mayeither be of one piece with the bolt 5 or, as in this embodiment (seeFIG. 3), may be made fast therewith by being provided with a threadedbore through which the bolt 5 is passed. The recess 9 extends to thearea where the edge face sections 12 extend in parallelism with thelongitudinal axis of the sleeve 11 and its configuration not only servesto effect expansion of the shell sections 4a and 4b in cooperation withthe expander member 7, but also to reduce friction during suchexpansion. The expander member 7, when withdrawn towards the portion 2by the bolt 5, acts in the same manner as a wedge and forces the shellsections 4a and 4b apart. Because the expander member 7 is securelyguided in the recess 9 by engagement with the sections 11, it isreliably secured against turning movement when the bolt 5 is turned in asense withdrawing the expander member 7 towards the portion 2 of thesleeve 1.

It is also advantageous, and provided in the embodiment of FIGS. 1 and3, to form transverse slots 13 which extend inwardly from the sections12 in the two shank wall portions of the respective shell sections andterminate at or at least in the proximity of the bight wall portionassociated with the respective shank wall portions. These slots arelocated just forwardly of the location 3 where the shell sections 4a and4b are connected with one another and their provision forms the sleeve 1with two strip-shaped wall portions 14a and 14b which are offset withrespect to the plane of separation of the shell sections 4a and 4bthrough in each case, and which in effect as pivots about which theshell sections 4a and 4b can be radially outwardly deflected as shown inFIG. 3, when the expander member 7 is drawn rearwardly in the directiontowards the end portion 2. It will be appreciated that the relativelynarrow stripshaped wall portions 14a and 14b provide very littleopposition to the radially outward deflection, thereby reducing theforce required for drawing the expander member 7 into the sleeve.

It will be seen in FIG. 3 how the soft and/or porous material of thesupport structure 17 is compacted by the radially outward deflection ofthe shell sections 40 and 4b, after the expansion anchor is insertedinto the expansion anchor hole 19 provided for this purpose in thesupport structure 17.

FIG. 2 illustrates a further embodiment of the invention according towhich the shell sections 4a and 4b of the sleeves 1' overlap one anotheror are partly encapsulated one within the other. In this construction aneven more significant expansion of the shell sections is made possiblebecause the expander member 7 slides on the sections 11 which overlapone another as shown in FIG. 2, so that the expander member can expandthe shell sections 4a and 4b even further than in the embodiment ofFIGS. 1 and 3. In- FIG. 2 the crosssectional configuration of the shellsections 411' and 4b is again substantially U-shaped, but of angularrather than rounded configuration to make possible a maximum overlappingof the shell sections without any significant reduction of thecross-section of the inner passage defined between them. The sleeve l'is of course in this case of quadratic or rectangular cross-section, aconfiguration which affords an additional advantage in that itinherently precludes undesired turning of the sleeve in the expansionanchor hole when the bolt 5 is turned in a sense drawing the expandermember 7 deeper into the sleeve.

The shell sections 4a and 4b in this embodiment are connected with oneanother by several-here four-depressions or kerfs in the overlappingshank walls of the respective shell sections, and the projectionsresulting at the interior of the respective shell sections from theprovision of the depression 15 have a cross-section across the centralpassage of the sleeve 1 which corresponds to the outer diameter of thebolt 5 to serve as a guide therefor.

In this embodiment the bight walls of the respective shell sections 4aand 4b extend beyond the shank walls and forwardly of the leading end ofthe sleeve 1, being bent towards one another transversely of thelongitudinal axis of the sleeve and across the recess 9 to form a cap 16which is of one piece with the sleeve.

In the embodiment of FIG. 4, finally, the fragmentarily illustratedsleeve 1 is similar to the sleeve of FIGS. 1 and 3. It is, however,provided with a separate cap l8-by contrast to the integral cap in FIG.2-- which is placed onfor instance pushed on and for instancefrictionally retained onthe leading end of the sleeve 1 and which servesto prevent the expander member 7 from being driven inwardly into thesleeve when the expansion anchor is forcibly inserted into an expansionanchor hole; this precludes premature expansion of the shell sections 4aand 4b. It is particularly advantageous, and frequently even necessary,when the expansion anchor hole which is separately formed andaccommodates the anchor, has dimensions which are smaller than the outerdimensions of the sleeve. The cap 18 must of course engage and besupported by the sleeve, and not by the expander member 7 and must be soconfigurated that it does not interfere with the subsequent radialexpansion of the sleeve, for which purpose the portions of the cap areadvantageously made so thin that they will break off or at least yieldin outward direction in response to even a slight force tending toexpand the shell sections 4a and 4b. It is also advantageous to make thecap 18 pointed in forward direction to facilitate its insertiontogetherwith the remainder of the expansion anchor-into an expansion anchorhole, particularly a tight one.

The cap 18, as well as the integral cap 16 of FIG. 2, also serves toprevent the expander member 7 from falling out of the recess 9 if forany reason the expander member is not connected with the bolt 5 or iffor instance the bolt 5 is not connected with the nut 6 in which casethe expander member and the bolt could slide out the leading end of thesleeve together.

To prevent the expander member 7 from slipping, especially on thesections 12 when it is drawn into the sleeve in a sense expanding it, itis also advantageous to have it extend slightly outwardly beyond theouter periphery of the sleeve and to form it with slits or recesses 21in its circumference, as illustrated in broken lines in FIG. 4, in whichslits or recesses 21 the sections 11 and, depending upon the extent towhich the expander member 7 is drawn into the sleeve, subsequently thesections 12, are partly accommodated so as to guide the expander member7. This is particularly advantageous when the lateral play of the bolt 5is large enough so that the expander member 7 could slide offthat is outof engagement with-the sections 11 and- /or 12.

It will be appreciated that various modifications will offer themselvesreadily to those skilled in the art. The configuration of the expandermember 7 may be changed, as long as its dimension transversely of theaxis of the sleeve fulfills the requirements outlined earlier, and ofcourse also the configuration of the shell sections themselves may bevaried.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in anexpansion anchor, it is not intended to be limited to the details shown,since various modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic and specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent isset forth in the appended:

1. An expansion anchor for use in support structures of relatively softmaterial, comprising an expansion anchor sleeve having a front portionand a rear portion and comprising a pair of elongated shell sections ofsubstantially U-shaped cross-section, each having a pair ofsubstantially parallel side walls bounded at one side by edge faces andintegrally joined at the other side by a bight wall angularly related tosaid side walls, the side walls of one of said shell sectionsoverlapping the side walls of the other shell section and the bightwalls of said shell sections facing each other to define with said sidewalls a space of substantially rectangular configuration; a transverserecess in said front portion and bounded by sections of said edge faceswhich converge from said front portion towards said rear portion, eachedge face section extending from the bight wall of one shell sectiontowards the bight wall of the other shell section and having on theoverlapping portion of the respective side wall an upper end adjacentsaid bight wall of the other shell section; an expander member locatedin said recess and extending transversely to the elongation of saidsleeves; and threaded means extending from the region of said rearportion towards said front portion and being fast with said expandermember, turning of said threaded means in the requisite sense resultingin displacement of said expander member in direction towards said rearportion in sliding engagement with said edge faces and leading to aconcomittant outward deflection of said shell sections at least in theregion of said front portion.

2. An expansion anchor for use in support structures of relatively softmaterial, comprising an expansion anchor sleeve having a front portionand a rear portion and comprising a pair of elongated shell sections ofsubstantially U-shaped cross-section, each having a pair ofsubstantially parallel side walls bounded at one side by edge faces andintegrally joined at the other side by a bight wall, the side walls ofone of said shell sections overlapping the side walls of the outer shellsection and the bight walls of said shell sections facing each other; atransverse recess in said front portion and bounded by sections of saidedge faces which converge from said front portion towards said rearportion, each edge face section extending from the bight wall of oneshell section towards the bight wall of the other shell section andhaving an upper end located on the portion of the respective side wallwhich substantially overlaps the other side wall; an expansion memberlocated in said recess and extending transversely to the elongation ofsaid sleeve; and threaded means extending from the region of said rearportion towards said front portion and being fast with said expandermember, turning of said threaded means in requisite sense resulting indisplacement of said expander member in direction towards said rearportion in sliding engagement with said edge faces and leading to aconcomittant outward deflection of said shell sections at least in theregion of said front portion.

3. An expansion anchor as defined in claim 2; and further comprisingconnecting means connecting said shell sections with one another in theregion of said rear portion.

4. An expansion anchor as defined in claim 3, said connecting meanscomprising interengaging notches and projections provided on therespective shell sections in the region of said rear portion.

5. An expansion anchor as defined in claim 3, and further comprisingslots provided in said side walls forwardly of said connecting means andextending at least to the proximity of the respective bight wall.

6. An expansion anchor as defined in claim 2; and further comprising acap covering and extending forwardly of said front portion.

7. An expansion anchor as defined in claim 6, wherein said cap is of onepiece with said sleeve.

8. An expansion anchor as defined in claim 9, and wherein each of saidbight walls comprises a wall portion extending forwardly of said sidewalls and of the leading end of said front portion, said wall portionsextending towards one another transversely of a longitudinal axis ofsaid sleeve and across said recess and together constituting said cap.

1. An expansion anchor for use in support structures of relatively softmaterial, comprising an expansion anchor sleeve having a front portionand a rear portion and comprising a pair of elongated shell sections ofsubstantially U-shaped crosssection, each having a pair of substantiallyparallel side walls bounded at one side by edge faces and integrallyjoined at the other side by a bight wall angularly related to said sidewalls, the side walls of one of said shell sections overlapping the sidewalls of the other shell section and the bight walls of said shellsections facing each other to define with said side walls a space ofsubstantially rectangular configuration; a transverse recess in saidfront portion and bounded by sections of said edge faces which convergefrom said front portion towards said rear portion, each edge facesection extending from the bight wall of one shell section towards thebight wall of the other shell section and having on the overlappingportion of the respective side wall an upper end adjacent said bightwall of the other shell section; an expander member located in saidrecess and extending transversely to the elongation of said sleeves; andthreaded means extending from the region of said rear portion towardssaid front portion and being fast with said expander member, turning ofsaid threaded means in the requisite sense resulting in displacement ofsaid expander member in direction towards said rear portion in slidingengagement with said edge faces and leading to a concomittant outwarddeflection of said shell sections at least in the region of said frontportion.
 2. An expansion anchor for use in support structures ofrelatively soft material, comprising an expansion anchor sleeve having afront portion and a rear portion and comprising a pair of elongatedshell sections of substantially U-shaped cross-section, each having apair of substantially parallel side walls bounded at one side by edgefaces and integrally joined at the other side by a bight wall, the sidewalls of one of said shell sections overlapping the side walls of theouter shell section and the bight walls of said shell sections facingeach other; a transverse recess in said front portion and bounded bysections of said edge faces which converge from said front portiontowards said rear portion, each edge face section extending from thebight wall of one shell section towards the bight wall of the othershell section and having an upper end located on the portion of therespective side wall which substantially overlaps the other side wall;an expansion member located in said recess and extending transversely tothe elongation of said sleeve; and threaded means extending from theregion of said rear portion towards said front portion and being fastwith said expander member, turning of said threaded means in requisitesense resulting in displacement of said expander member in directiontowards said rear portion in sliding engagement with said edge faces andleading to a concomittant outward deflection of said shell sections atleast in the region of said front portion.
 3. An expansion anchor asdefined in claim 2; and further comprising connecting means connectingsaid shell sections with one another in the region of said rear portion.4. An expansion anchor as defined in claim 3, said connecting meanscomprising interengaging notches and projections provided on therespective shell sections in the region of said rear portion.
 5. Anexpansion anchor as defined in claim 3, and further comprising slotsprovided in said side walls forwardly of said connecting means andextending at least to the proximity of the respective bight wall.
 6. Anexpansion anchor as defined in claim 2; and further comprising a capcovering and extending forwardly of said front portion.
 7. An expansionanchor as defined in claim 6, wherein said cap is of one piece with saidsleeve.
 8. An expansion anchor as defined in claim 7, and wherein eachof said bight walls comprises a wall portion extending forwardly of saidside walls and of the leading end of said front portion, said wallportions extending towards one another transversely of a longitudinalaxis of said sleeve and across said recess and together constitutingsaid cap.